Conventionally, the technique of using resin to mold a vehicular panel member for the purpose of reducing the weight of a vehicle has been known. A left and right pair of roof side rails are disposed extending in a vehicle front-and-rear direction on both vehicle width direction end portions of a roof portion positioned on the upper portion of the vehicle, and a front header and a rear header disposed extending in the vehicle width direction are joined to front end portions and rear end portions, respectively, of the roof side rails.
For example, in patent document 1, a resin roof panel is joined to metal vehicle frame members, such as the front header, the rear header, and the roof side rails. Ribs are formed on an undersurface side (the opposite side of the design surface) of the roof panel along the vehicle front-and-rear direction on both end sides in the vehicle width direction, and because of this, the rigidity of the roof panel is raised.    Patent Document 1: JP-A No. 2008-68765